1. Field of the Invention
The present invention relates to a calibration method for the measurement of relative concentration of gas or vapor.
The invention also concerns a sensor construction applicable for the implementation of the method.
2. Description of Related Art
In this context, the relative concentration of gas or vapor is understood to refer to the ratio, which is the absolute concentration of the gas divided by the concentration of the gas at its saturation level. The relative concentration is conventionally used in, for instance, the determination of water vapor concentration (relative humidity).
The principal characteristics of measurement equipment are defined in terms of reliability and accuracy. For verification of these, different calibration methods are required.
An ideal solution for field calibration would be some form of automatic self-calibration. The implementation of this kind of self-calibration would be extremely difficult for most parameters.
Presently, most measurement instruments for relative concentration of gases and vapors are calibrated in controlled laboratory conditions.
A disadvantage of the prior art technology is that due to the awkward calibration routine, long calibration intervals are applied. Furthermore, this results in inaccurate measurements, because relative concentration meters are unstable by nature.